"The Adventure of the Blue Carbuncle" is the seventh story of twelve in The Adventures of Sherlock Holmes. The story was first published in Strand Magazine in January 1892. In "The Empty Hearse", the first episode of the third series of the BBC television series Sherlock, Sherlock Holmes and his brother Mycroft have a casual competition in deduction over analysing a particular knitted hat. When Mycroft determines that it belonged to a man, Sherlock asks, "Why, the size of the head?", to which Mycroft reproachingly replies, "Don't be silly. Some women have large heads, too." Sherlock's subsequent look of guilt is a satirical allusion to the phrenology involved in the original short story, where Sherlock Holmes deducted that an owner of a hat was intelligent based on the size of his head, remarking "a man with so large a brain must have something in it."
